How to make a great hamburger is a question that has bedeviled the nation for generations, for as long as Americans have had griddles and broilers, for as long as summertime shorts-wearing cooks have gone into the yard to grill.

But the answer is simple, according to many of those who make and sell the nation’s best hamburgers: Cook on heavy, cast-iron pans and griddles. Cook outside if you like, heating the pan over the fire of a grill, but never on the grill itself. The point is to allow rendering beef fat to gather around the patties as they cook, like a primitive high-heat confit.

“That is the best way to do it,” said George Motz, the documentary filmmaker who released “Hamburger America” in 2005 and has since become a leading authority on hamburgers. The beef fat collected in a hot skillet, Motz said, acts both as a cooking and a flavoring agent. “Grease is a condiment that is as natural as the beef itself,” he said. “A great burger should be like a baked potato, or sashimi. It should taste completely of itself.”

Michael Symon, the ebullient television Iron Chef, a host of ABC’s “The Chew” and a proprietor of a small chain of Midwestern hamburger restaurants called B Spot, agreed. Symon’s restaurants each serve more than 1,000 hamburgers a night, he said, all of them finished on a flat-top griddle coated in beef fat.

“Use a skillet,” he said. He was emphatic about the subject. “A grill is too difficult,” he said. “A hot skillet is what you want.”

We will return to the business of how to use that skillet, for — as Symon hastened to add — the surface on which you cook is only one component of hamburger excellence. There is also the size of the hamburger. There is the kind of meat used to create it. There is the bun. There is cheese or there is not. There are tomato debates, lettuce quarrels (on top or on the bottom?). There are questions of ketchup, of mustard, of pickles, of onions.

Some of these things are matters of personal taste, but for people who know burgers well, there is little disagreement about the best practices for making an exceptional one.

Two kinds of burgers

It is best to start at the beginning. Great hamburgers fall into two distinct categories. There is the traditional griddled hamburger of diners and take-away spots, smashed thin and cooked crisp on its edges. And there is the pub- or tavern-style hamburger, plump and juicy, with a thick char that gives way to tender, often blood-red meat within.

The diner hamburger has a precooked weight of 3 to 4 ounces, roughly an ice-cream-scoop’s worth of meat. The pub-style one is heavier, but not a great deal heavier. Its precooked weight ought to fall, experts say, between 7 and 8 ounces.

“Most of the time, 7 ounces is more than enough,” said Geoffrey Zakarian, the chef and owner of the National Bar and Dining Rooms, in New York, which serves a fine hamburger of roughly that size. Zakarian cautioned against hamburgers of more than a half-pound in weight. “You want to get some heat to the inside of the burger,” he said. “You don’t want some giant, underdone meatloaf.”

Whichever style you cook, pay close attention to the cuts of beef used in the grind. The traditional hamburger is made of ground chuck steak, rich in both fat and flavor, in a ratio that ideally runs about 80 percent meat, 20 percent fat. Less fat leads to a drier hamburger. Avoid, the experts say, supermarket blends advertised with words like “lean.”

Too much fat, on the other hand, can lead to equally troubling issues, and a mess in both fact and flavor. “You get up around 30 percent fat,” Symon said, and there are risks. “Things happen,” he said. “Bad things. Shrinkage.” Home cooks should experiment, he said, with blends that contain from 20 to 25 percent fat.

Restaurateurs, sometimes driven by the marketing efforts of celebrity butchers, tout hamburger blends of chuck and brisket, hanger and strip steak, short rib and clod. In New York, Pat LaFrieda Meat Purveyors has built a carriage-trade business on the back of whimsical blends of beef for hamburgers, in particular the custom Black Label blend put together for Keith McNally’s Minetta Tavern, in Manhattan. The particulars of that blend are kept secret by LaFrieda, but he has allowed that about 30 percent of it is dry-aged New York strip steak.

There are pitfalls to buying preground supermarket chuck steak, experts say. In addition to concerns about the health risks associated with preground hamburger meat, there are culinary considerations as well. The grind most markets use is “fine,” which means the fat globules in it are small. That can lead to the dreaded mushy mouth feel of a substandard hamburger. Better (and safer) to have a butcher grind your meat, asking for a coarse grind so that the ratio of meat to fat is clear to the eye.

Whatever the blend, it is wise to keep the meat in the refrigerator, untouched, until you are ready to cook. “Hamburgers are one of the few meats you want to cook cold,” Symon said. “You want the fat solid when the patty goes onto the skillet. You don’t want any smearing.”

Delicate art of patties

Forming the patties is a delicate art. For the thin, diner-style hamburger, Motz said, simply use a spoon or an ice-cream scoop to extract a loose golf ball of meat from the pile, and get it onto the skillet in one swift movement. “You don’t need to set the heat below it to stun,” he said. “A medium-hot pan will do it, accompanied for the first burger with a pat of melted butter to get the process started.”

Then, a heresy to many home cooks: the smash. Use a heavy spatula to press down on the meat, producing a thin patty about the size of a hamburger bun. “Everyone freaks out about that,” Motz said. “But it’s the only time you’re touching the meat, and you’re creating this great crust in doing it.” Roughly 90 seconds later, after seasoning the meat, you can slide your spatula under the patty, flip it over, add cheese if you’re using it, and cook the hamburger through.

The pub-style burger is in some ways even easier to make. The key, Symon said, is not to handle the meat too much. “A lot of people make the mistake of packing the burger really tightly,” he said. “But what you want is for it just to hold together, no more.” Simply grab a handful of beef and form it into a burger shape, then get it into the pan, season it and cook for about three minutes. Then turn it over and, if using, add cheese. The burger is done three to four minutes later for medium-rare.

“Most people don’t melt the cheese enough,” Zakarian said. He emphasized the need to dress the hamburger with cheese as soon as the patty is flipped. “You want a curtain of cheese to enrobe the meat,” he said. “The rennet in it really adds a lot of flavor.”

Which cheese you use is a matter of preference, but Motz does not sneeze at the highly processed slice that has covered the nation’s hamburgers since the early days of White Castle restaurants. “American cheese is designed to melt,” he said, “and it has 50 percent more sodium than cheddar or Swiss, so it adds a lot of flavor while also helping to hold the smashed patty together.”

In choosing buns, restaurateurs may offer hamburgers on special brioche from Balthazar, or fancy English muffins from Bays. But home cooks can do very well indeed with more commercial options, in particular potato buns, which offer a soft and sturdy platform for the meat.

The most important factor is, again, ratio. “The bun-to-burger ratio is incredibly important,” Symon said. “You want a soft bun, like a challah or potato, but whichever you use it shouldn’t overwhelm the burger. They should be as one.”

Finally, there are condiments. You pull your burgers off the skillet, place them on the buns and then offer them to guests to dress. Ripe tomatoes and cold lettuce should be offered (“Only bibb lettuce,” Zakarian said, “for its crispness and ability to hold the juices of the meat”) along with ketchup, mustard and, for a hardy few, mayonnaise or mayonnaise mixtures. Onions excite some. Pickles, others.

1. Add oil or butter to a large cast-iron or stainless-steel skillet and place over medium heat. Gently divide ground beef into eight small piles of around 4 ounces each, and even more gently gather them together into orbs that are about 2 inches in height. Do not form patties.

2. Increase heat under skillet to high. Put half the orbs into the skillet with plenty of distance between them and, using a stiff metal spatula, press down on each one to form a burger that is around 4 inches in diameter and about ½ inch thick. Season with salt and pepper.

3. Cook without moving until patties have achieved a deep, burnished crust, a little less than two minutes. Use the spatula to scrape free and carefully turn burgers over. If using cheese, lay slices on meat.

4. Continue to cook until meat is cooked through, approximately a minute or so longer. Remove burgers from skillet, place on buns and top as desired. Repeat process with remaining burgers. Serving two hamburgers on a single bun is not an outrageous option.

HAMBURGERS (TAVERN STYLE)

Makes 4 servings

½ teaspoon neutral oil, like canola, or a pat of unsalted butter

2 pounds ground chuck, at least 20 percent fat

Kosher salt and black pepper to taste

4 slices cheese (optional)

4 soft hamburger buns

Lettuce leaves, sliced tomatoes and condiments, as desired

1. Add oil or butter to a large cast-iron or stainless-steel skillet and place over medium heat. Gently divide ground beef into four small piles of around 8 ounces each, and then lightly form these into thick patties of around 3½ inches in diameter, like flattened meatballs. Season aggressively with salt and pepper.

2. Increase heat under skillet to high. Put hamburgers into the skillet with plenty of distance between them and allow them to cook, without moving, for approximately three minutes. Use a spatula to turn hamburgers over. If using cheese, lay slices on meat.

3. Continue to cook until meat is cooked through, approximately another three to four minutes for medium-rare. Remove hamburgers from skillet and allow to rest for approximately five minutes; meanwhile, toast the buns. Place hamburgers on buns and top as desired.